Automotive applications using silicone rubber are constantly challenged to demonstrate performance improvements. Technology trends result in demands for ever increasing resistance to both heat and chemical exposure. For example, Western Europe continues to exhibit significant growth in turbo diesel passenger cars, at the expense of their gasoline equivalents. In the U.S., a similar growth has been experienced in the small truck market. The service temperatures and pressure of the hoses, especially turbo diesel engine hoses, are thus increasing. Typically, the hoses used in automotive applications have a multilayer structure consisting of fabric reinforcement encapsulated with silicone rubber (classified as VMQ elastomer by the American Society of Test Methods (ASTM)) and lined internally with a layer of fluoroelastorner (FVMQ).
There is a need to improve the heat stability of the silicone elastomers used in automotive applications, and in particular for their use in o-rings, connectors, and in the construction of hoses.
The present inventors have discovered a stabilizer, that when added to silicone elastomer base compositions, provide improved heat aging properties to the cured silicone elastomer.